The present invention relates generally to arrangements adapted for removing moisture, and more specifically, it relates to a method and apparatus for removing moisture from interior spaces.
Arrangements for removing moisture from enclosures or interior spaces are widely used in industries in which products stored in the enclosed or interior spaces must be maintained at a sufficiently low moisture level or content to preserve their functional integrity. The ability to maintain reduced moisture levels is particularly critical in laboratory cabinets and related storage enclosures, since such enclosures are commonly used to store chemicals, materials, products and equipment particularly susceptible to moisture damage. For example, elevated moisture levels within laboratory cabinets can cause contamination of chemicals, materials and other substances stored therein. In similar fashion, the precision and functionality of chemical handling and measurement equipment can often be undesirably compromised by such exposure.
Conventional dehumidifying arrangements include a blowing mechanism, such as a rotating fan, positioned within a housing and functioning to draw a flow of moisture-filled air into at one end of a housing and through a desiccant medium, with the moisture transferred to the desiccant medium and the dried air emerging from an opposite end of the housing. Periodically, the desiccant medium in such conventional apparatus becomes saturated with moisture, requiring either replacement or regeneration of the desiccant for subsequent drying of the air in the enclosure. In the latter instance, desiccant drying can be accomplished by facilitating a reverse flow of heated air through the desiccant to remove the moisture from, and thereby regenerate the desiccant. For laboratory cabinet applications, it would be desirable to have such an apparatus separate the flow path of the cabinet drying air from the flow path of the desiccant regenerating air such that the undesirable flow of moist regeneration air from the desiccant back into the enclosed cabinet space is avoided.
Moisture removing and controlling apparatus are known in the prior art. However, these known moisture-removing devices generally suffer from one or more drawbacks and limitations which render them undesirable for the aforementioned laboratory cabinet applications. For example, U.S. Pat. No. 4,361,425 discloses a dehumidifier having a moisture-collecting chamber which contains a loose or preformed solid desiccant. The chamber is connected to a conventional drain valve that operates automatically periodically for draining the moisture from the chamber. A high-speed fan is installed adjacent to the chamber for subjecting compressed air passing therethrough to centrifugal force, thereby removing moisture and foreign particles from the compressed air. Accordingly, the dehumidifier disclosed in the ""425 patent is specifically designed for removing moisture from compressed air rather than from air generally confined in an interior space. Moreover, the design requirements of the particular application do not permit self-regeneration of the desiccant, which must be periodically removed from the moisture-collecting chamber and replaced. U.S. Pat. Nos. 4,654,057 and 5,230,719 are exemplary of other types of known moisture removal, or dehumidifying, apparatus. However, these disclosed exemplary devices draw the moist air to be dried into one end of a housing and discharge the dried air from the opposite end of the housing. Regeneration or drying of the desiccant requires reverse flow of air through the housing, discharging moist regeneration air back into the space from which moisture was removed during the drying step. Obviously such operational principle is unacceptable for the highly humidity sensitive environment of the laboratory equipment. U.S. Pat. Nos. 4,536,198; 5,297,398; 5,373,704; 5,799,728; 6,364,942; and 6,379,435 disclose examples of other types of moisture-removing apparatus which suffer from one or more of the aforementioned drawbacks and limitations, rendering them non-conducive or undesirable for use with laboratory enclosures.
Accordingly, there is a well-established need for a moisture-removing apparatus or desiccation unit adapted for removing moisture from, and maintaining a dry environment within, enclosed such as laboratory cabinets. In particular, it would be desirable to provide a moisture-removing and controlling apparatus or desiccation unit which is compact in design, relatively simple in construction, self-contained, self-regenerating and which may be readily incorporated in a variety of cabinets or other enclosures for the efficient and effective removal of moisture from their interior. Furthermore, it would be desirable to provide such a desiccation unit that is highly reliable in operation and lends itself to cost-effective manufacture and ease of installation.
The invention is directed to an apparatus for removing moisture from cabinets or other enclosed spaces, and is particularly adapted for, but not limited to, use in laboratory cabinets. The apparatus has a compact, efficient and self-contained design that facilitates both the thorough drying of air within the cabinet as well as the regeneration of desiccant material used during the drying operation.
In one general aspect of the present invention, a moisture control apparatus is provided comprising:
a housing;
a desiccant chamber containing a desiccant medium provided in the housing;
a regeneration fan and a drying fan provided in the housing on opposite sides of the desiccant chamber;
a dry air outlet area and a moist air inlet area provided adjacent to one end of the housing; a regeneration air inlet area and a regeneration air outlet area provided adjacent to an opposite end of the housing; wherein moist air to be dried flows into the housing through the moist air inlet area, then through the desiccant chamber and desiccant medium and the dried air flows from the housing through the dry air outlet area, responsive to operation of the drying fan. The regeneration air which is adapted to dry the desiccant medium flows into the housing through the regeneration air inlet area, then through the desiccant chamber and desiccant medium and removes moisture from the desiccant. The moistened regeneration air flows from the housing through the regeneration air outlet area, responsive to operation of the regeneration fan.
In a further aspect of the present invention, flaps are provided at the moist air inlet area, the dry air outlet area, the regeneration air inlet area and the regeneration air outlet area, respectively. During the air drying step, the flap at the moist air inlet area and the flap at the dry air outlet area are opened to facilitate flow of air into and out of, respectively, the housing, whereas the flap at the regeneration air outlet area is pulled to a closed position by vacuum pressure in the housing and the flap at the regeneration air inlet area is pushed to a closed position by positive pressure in the housing to prevent flow of air into the housing through those areas. During the desiccant regeneration step, the flap at the regeneration air inlet area and the flap at the regeneration air outlet area are forced open by the incoming and outgoing regeneration air, respectively, whereas the flap at the dry air outlet area is forced into a closed position by vacuum pressure in the housing, and the flap at the moist air inlet area is forced into a closed position by positive pressure in the housing, thereby preventing the flow of air into the housing through those areas.
In still a further aspect of the present invention, an access panel is removably attached to the housing to facilitate the eventual replacement of desiccant medium as well as maintenance of interior housing components.
In another aspect of the present invention, a microprocessor-based controller is operably connected to the regeneration fan, the drying fan and the heating elements in the desiccation chamber for automatically cycling operation thereof. The controller may include an automatic shut-off mechanism for terminating operation of any or all of these components in the event of malfunctioning or excessive heat generation.
In yet a further aspect of the present invention, the housing is provided with an inlet opening and an outlet opening for the flow of moist air to be dried from an interior enclosure, into the housing, through the desiccant medium, out of the housing, and back into the interior enclosure in a dried state. The housing is further provided with another inlet opening and another outlet opening for the flow of desiccant-drying regeneration air from outside the enclosure, into the housing, through the desiccant medium, and out of the housing back into the ambient air surrounding the enclosure.
Still another aspect of the present invention provides a moisture-removing apparatus or desiccation unit that is lightweight, compact, efficient, self-regenerating and capable of use in a variety of enclosures.
These and other aspects, features, and advantages of the present invention will become more readily apparent from the attached drawings and the detailed description of the preferred embodiments, which follow.